Cross-docking is a practice in the logistics industry wherein materials are unloaded from an incoming semi-trailer truck or railroad car, and loaded directly onto outbound trucks, trailers, or rail cars, with little or no storage in between. This may be done to change the type of material carrier, to sort material for different destinations, or to combine material from different origins into transport vehicles (or containers) with the same or similar destinations.
Cross-docking is done with various vehicles, including forklifts and yard or terminal tractors. One such tractor, shown in FIG. 1, is the Pro-Spotter built by TICO Manufacturing of Ridgeland, S.C., which is used at distribution centers, rail terminals and ports. These tractors are smaller than full-sized “semis,” and are designed to transport relatively small freight, sometimes referred to as less-than-truckload or LTL shipping, with freight that occupies only a portion of an entire trailer. Multiple shippers can share space on the same truck, only paying for their portion, making LTL a cost efficient method of shipping freight.
In the LTL trucking industry, cross-docking is done by moving cargo from one transport vehicle directly onto another, with minimal or no warehousing. In retail practice, cross-docking operations may utilize staging areas where inbound materials are sorted, consolidated, and stored until the outbound shipment is complete and ready to ship. Terminal tractors that are then used to “spot” trailers to and from the doors of the terminal.
While some cross-docking tractors are diesel-powered, TICO recently introduced a Pro-Spotter that runs on LPG (as used herein, Liquefied Petroleum Gas; Liquefied Propane Gas; or simply “propane”). As an alternative to conventional diesel fueled terminal tractors, LPG is a cleaner fuel that eliminates the need for bulk diesel storage on site with associated environmental issues. Diesel-powered terminal tractors must also be DOT certified to travel on public streets to go to a fueling facility with attendant diesel emissions maintenance complications.
Many facilities, including LTL cross-dock terminals, currently use large numbers of forklifts powered by individual, portable LPG cylinders. Such cylinders enable efficient refueling (i.e., by swapping). Like many industries, high throughput is essential the cross-docking industry. While LPG-powered terminal tractors come equipped with a single, primary LPG fuel tank, down-time may be incurred when this larger tank requires refilling.